netdev - Re: [PATCH] xfrm: Fix oops in __xfrm_state

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Date:   Tue, 1 Nov 2022 20:10:21 +0100
From:   Antony Antony <antony.antony@...unet.com>
To:     Herbert Xu <herbert@...dor.apana.org.au>
CC:     Thomas Jarosch <thomas.jarosch@...ra2net.com>,
        Steffen Klassert <steffen.klassert@...unet.com>,
        Antony Antony <antony.antony@...unet.com>,
        Sabrina Dubroca <sd@...asysnail.net>,
        Leon Romanovsky <leon@...nel.org>,
        "Roth Mark" <rothm@...l.com>, Zhihao Chen <chenzhihao@...zu.com>,
        Tobias Brunner <tobias@...ongswan.org>,
        <netdev@...r.kernel.org>
Subject: Re: [PATCH] xfrm: Fix oops in __xfrm_state_delete()

On Tue, Nov 01, 2022 at 12:39:48 +0800, Herbert Xu wrote:
> On Mon, Oct 31, 2022 at 04:26:12PM +0100, Thomas Jarosch wrote:
> >
> > diff --git a/net/key/af_key.c b/net/key/af_key.c
> > index c85df5b958d2..65a9ede62d65 100644
> > --- a/net/key/af_key.c
> > +++ b/net/key/af_key.c
> > @@ -3382,7 +3382,7 @@ static int pfkey_send_new_mapping(struct xfrm_state *x, xfrm_address_t *ipaddr,
> >  	hdr->sadb_msg_len = size / sizeof(uint64_t);
> >  	hdr->sadb_msg_errno = 0;
> >  	hdr->sadb_msg_reserved = 0;
> > -	hdr->sadb_msg_seq = x->km.seq = get_acqseq();

This line looks very odd.

> > +	hdr->sadb_msg_seq = get_acqseq();
> 
> This looks broken.  x->km.seq is part of the state which you are
> changing.  Shouldn't you do whatever xfrm_user does in the same
> situation?

xfrm_user sets msg_seq to zero in mapping change message. seq is only useful for
acquire message. I think setting to zero would be a better fix.

-	hdr->sadb_msg_seq = x->km.seq = get_acqseq();
+	hdr->sadb_msg_seq = 0;

While increasing x->km.seq in every call to pfkey_send_new_mapping()
could be an issue, would it alone explan the crash?

Tobias would pfkey_send_new_mapping() called in a default setting?